Internet users may use one or more email addresses but generally limit their use to a handful of addresses. These addresses are used for different purposes ranging from personal email, work email, email addresses for websites, and other uses. All of these addresses are given to a wide range of senders within that use case. For personal email, the address may be given to friends, family members, and acquaintances. This means that dozens, if not hundreds or thousands, of people or services know a single email address to contact an individual. If any of these individuals begin sending unwanted email or if their accounts are compromised and a recipient's address is harvested by identity thieves or spammers, the individual whose information has been compromised or is being misused has no method of stopping the tide of unwanted email other than changing their email address. If a user does change their email address they would need to inform all of their contacts of the change of address which opens them up to the same issue in the future. This is a cumbersome approach to solving the problem to maintaining email address security and privacy and does not accomplish the goal aside from a small window of time when no information is compromised.
Prior art exists in the form of detecting spam and unwanted email after this email is already delivered to the user. This type of ability is employed by most major email service providers and many independent companies focus solely on rating the validity of an email based on various factors including content, subject line, sender address, sender location, etc. But these approaches do not take an active approach to validating senders before accepting their email content for delivery to the recipient.